Ruthenium or ruthenium compounds have been used as a raw material for thin film electrodes of semiconductor devices such as DRAM and FERAM. Chemical deposition such as CVD (chemical vapor deposition) or ALD (atomic layer deposition) has been applied to the production of such thin films. And many organoruthenium compounds have been known as raw material compounds used in chemical vapor deposition. For example, bis(ethylcyclopentadienyl)ruthenium represented by the following formula is a compound most frequently used as such a raw material.    Patent Document 1: Japanese Patent Application Laid-Open No. 11-35589

Many of previously known organoruthenium compounds, including bis(ethylcyclopentadienyl)ruthenium described above, require oxygen exists with them when they are formed into thin films so that they can be decomposed. Thus, in conventional thin film production, it is indispensable to introduce into the reactor oxygen, as a reactant gas, together with vaporized organoruthenium gas. However, in the thin film formation in the presence of oxygen, there is a fear that oxygen remains in the resultant thin film, causing the problem of deterioration in morphology and electric properties of the produced thin film.
Recently, there have been increasing demands for an organoruthenium compound which can be decomposed and formed into a thin film even in the absence of oxygen, and the application of (1,5-cyclooctadiene)(toluene)ruthenium represented by the following formula, as an organoruthenium compound as described above, has been considered. The organoruthenium compound including ruthenium and 1,5-cyclooctadiene, as a diene group, and toluene, as an arene group, coordinated to the ruthenium is a compound which can be decomposed by heating even in the absence of oxygen.    Non-Patent Document 1: Andreas Schneider et al., Chem. Vap. Deposition 2005, 11, No. 2, p. 99-105
